Silver halide photographic element containing spot or streak prevention compounds



United States Patent ABSTRACT OF THE DISCLQSURE Photographic elements having a Water-permeable colloid silver halide emulsion layer and containing in a waterpermeable layer thereof one or more compounds containing the nucleus 0 on R wherein A contains the nucleus wherein X=-O-- or and wherein R is H, halogen or alkyl of 1-4 carbon atoms and R =H, alkyl of 1-4 carbons, aralkyl or aryl, and more particularly kojic acid and maltol.

This invention relates to photography, and more particularly to photographic elements bearing silver halide emulsion layers which elements are free from spots or streaks. The invention also relates to processes for preparing such elements.

As is known in the art, the manufacture of photosensitive photographic materials must be carried out in an atmosphere as nearly dustless as possible, since dust particles exert a deleterious effect on the photosensitive layer. Dust gains direct entry into coating and casting machines by way of the dry air required for drying the photosensitive layers. Further, dust particles are carried into the workrooms by operating personnel and, as a result of wear and corrosion, dust particles are formed in machines, in conveyor equipment, and in the factory rooms themselves. By filtering the air and observing special measures of cleanliness it is possible to keep dust formation down to the barest minimum but, primarily because of unavoidable Wear effects in production equipment, absolute dustlessness cannot be achieved.

Dust formed in the machines, or carried in, settles on the freshly coated films While they are still wet and introduces into the final processed material defects which are particularly conspicous for varieties of dust which react chemically with the photosensitive emulsion.

Among the particles of impurities which are most active chemically are light and heavy metals, their oxides and salts, and also, in particular, substances having acidic and basic reaction.

The harmful action of chemically active dust particles depends primarily on the fact that they exert reducing or oxidizing effects on the photosensitive layer and so interfere with photographic development, and that they also cause local shifts in pH, leading to changes in sensitivity. Light and dark spots and streaks occur in the final material after developing and fixing, due to the varying sensitizing and desensitizing effects. Since the causative particles or agents, or their reaction products, diffuse Within the photosensitive layer, the resulting spots and streaks have many times the dimensions of the causative agents themselves.

The appearance, size and intensity of the resulting defects depend chiefly on the time of action by the causative agent in the emulsion, the kind of emulsion, the rate of diffusion of ions of the causative agent, the length of storage time and also on the processing conditions used for the exposed material.

A few processes are already known from the literature, which are said to prevent these defects caused by chemically active dust particles.

For example, it is known in the art to add to the photosensitive material substances which have a good sequestering capacity for metal ions, such for example as metaphosphates and polyphosphates or hydroxylated polyaminopolycarboxylic acids, e.g., derivatives of imino-, hydrazino-, ethylenediaminodiand ethylenediaminotriacetic acids. It is also known in the art to combat spottiness by adding aldoximes and hydroxyketones such as hydroxyacetone, triose reductone, hydroxyacetophenone and the like.

Yet none of these methods is entirely satisfactory. In part, the pertinent agents lack the capacity for complete prevenion of spotting because they do not react With some of the interfering cations within the photochemically permissible pH range. Other substances, especially those disclosed in German Patent 1,124,353, belonging to the class of 1,2-enedio1s, have in part an extraordinarily high reducing activity and therefore tend to cause fogging under some conditions.

Now it has been found that compounds having the general formula shown below are especially adapted to prevention of spotting and that a particularly superior photosensitive material is accordingly obtained, in respect to the property mentioned above, when it contains in at least one layer, e.g., a water-permeable colloid layer, one or more compounds having the general formula:

A an R, R and R =H, halogen, e.g., C1 or Br; alkyl of 14 carbons, e.g., ethyl, methyl, propyl and 'butyl, and substituted alkyl groups, acyl groups, e.g., acetyl and benzoyl; carboxyl, carboxyamide or carboxylic acid ester groups with an alkanol of 1-4 carbons, e.g., methyl and ethyl; where R, R and R may be alike or different.

R =H, carboxyl, carboxyamide or carboxylic acid ester groups.

R =H, alkyl or carbalkoxy groups of 1-4 carbons as listed above.

R and R together may also represent a doublebonded oxygen atom.

R =H, alkyl of 14 carbons, as listed above, aralkyl,

e.g., benzyl; or aryl, e.g., phenyl and naphthyl, substituted or not.

Thus, the following compounds come under consideration as additives in accordance with this invention:

I I II II 0-0 0:0 011 HO C-OH II I I I on o I 11 III I-I1NOC;CO\ IIOCH2;CO\ o II II J a 110 0-011 0 011 o 011 g]: 0

1V v VI 11 1130oo0;o 0

HO 0-0000111 0=0 0-o11t I II 0-0 110-0 011 it) I I CONIIZ mozooo-o 0-0 0 0 0 11 1m 01 1 p o c 011 00 0 II n 0 011 0 IX X 1110000 01110000113 0 II 0000o0113 0 o II3O-N C-C-CH3 it 00 4 0 ii 0 011 2:1 XII 0 H 11 o-0 0001n 110 CN\ 0=0 ooo11 H H II 0 XIII Among the compounds shown above, kojic acid (Compound V in table above) and maltol (Compound III in table above) are outstanding for their high activity.

In efficacy as spotting inhibitors, the compounds to be added in accordance with this invention are superior to those known in the art for such purposes. This superiority is presumably attributable to the fact that, in addition to high complex-forming capacity, they have a high buffering capacity and so are capable of counteracting pH changes due to the action of acidic or basic substances and thus of eliminating all defects which occur as a result of such local shifts in pH.

Still better results can be obtained by using the additives in accordance with this invention in conjunction with salts, suitably alkali metal salts, e.g., a sodium or potassium salt of ethylenediaminetetraacetic acid. Because of its outstanding butfering capacity, this combination is suitable, for example, even for suppressing defects caused by inhomogeneous distribution of acidic or basic added substances which may be present in auxiliary layers, such as acids in substrate layers, antistatic agents or coating additives and the like.

The results obtained are particularly good when the compounds provided in accordance with this invention are used with salts of ethylenediaminetetraacetic acid in a mol ratio of 2:1.

Further, it must be pointed out that the compounds provided in accordance with this invention, in combination With salts of ethylen-ediamintetraacetic acid, have an antistatic eilect. It is known in the art that photosensitive photographic materials can acquire an electric charge due to friction effects in the manufacturing process. Aside from the fact that such electrically charged films or the like are subject to particularly severe dust deposits because they act as electrostatic precipitators, there is also the hazard that the photosensitive layer will be prematurely exposed to luminosity occurring during discharges. These drawbacks are eliminated by the substances provided in accordance with this invention when they are used in combination with salts of ethylenediaminetetraacetic acid.

An additional advantage of the additives according to this invention, and not the least, is that they are independent of pH within the pH range which is photochemically involved, so that their range of utility is in no wise restricted.

The additives in accordance with this invention are readily soluble in water and so are suitably incorporated with the photosensitive photographic layers in aqueous solution. The designated compounds may be added to the photosensitive layer, but they are also effective in auxiliary layers, such as the barytes layer, adhesive layers, e.g., gelatin, etc. sublayers; interlayers, e.g., gelatin filter layers; or protective coatings or antihalation coatings. If the addition is made directly to the photosensitive silver halide emulsion layer, it is preferable to use 025-05 g. per kg. of emulsion.

The optimum quantity for use from one case to another will of course depend on the type of emulsion being used and can always be ascertained, depending on the requirements, conveniently by appropriate trial tests and can be varied accordingly.

Even during prolonged storage, the compounds to be used in accordance with this invention do not impair either the sensitivity or the gradation of the photosensitive photographic material and accordingly can be used both in photosensitive photographic films and in photographic papers. Because of their good compatibility with emulison additives they can be used in orthochromatically and in panchromatically sensitized emulsions, as well as in unsensitized emulsions, e.g., X-ray emulsions. It has been found that the compounds provided in accordance with this invention can also be added, with excellent results, to color photography emulsions containing coupling agents.

Preparation of the compounds to be used in accordance with this invention is described in the literature and can be effected by the methods there set forth. A method for preparing 3-hydroxy-pyrone-(2) is described by Hasenfratz in Compt. rend. 184, 212, while the compound 3-hydroxypyridone-(4) can be prepared as described in J. prakt. Chem. (2) 27, 270.

The compounds maltol and kojic acid, which are particularly suited to the purposes of this invention, are commercial products, available on the market in adequate purity.

The following examples are intended to illustrate the invention without delimiting it in any way.

Example 1 There is applied to a cellulose triacetate film base a suspension of gelatin in organic solvents, containing 7 g. gelatin per liter, as an adhesive layer. A gelatin interlayer composed of a solution of gelatin in a water:methanol blend, containing 1 g. gelatin per liter, is coated over the adhesive layer.

Then a high-sensitivity silver bromideziodide (1.5% AgI) emulsion of the ammonia type, containing 7% gelatin and silver iodide at 0.73 mol/kg., is applied. The photosensitive layer is then given a customary gelatin protective coating.

During the preparation of this material, before applying the photosensitive emulsion, a metal dust obtained by grinding metals present in the coating machine con struction, is dusted onto the gelatin interlayer while it is still wet.

Two test strips A and B were now prepared, which differed in that the adhesive layer solution for strip B contained maltol (Compound III in the table above) at 4 g./liter of the solution used in making the adhesive layer.

After drying, the two test strips A and B were exposed, developed in a customary metolzhydroquinone developer, fixed in an acidic fixative bath and then dried. Strip A showed dark spots, while strip B was spotless.

Example 2 On the gelatin interlayer of a material constructed as in Example 1, after contaminating it with dust sweepings from the production room, a highly sensitive panchromatic neutral silver bromideziodide (5% AgI) emulsion suitable for portrait film was coated. It contained 10% gelatin and 0.33 mol/kg. of silver halide. One of the customary gelatin protective coatings Was then applied to the photosensitive layer. This material served as test specimen A. For the comparison specimen B, the same material was employed, with the difference that its gelatin interlayer contained pyrocomene amine acid (Compound II in the table above) at 1.5 g./liter of the slution employed in making the protective coating.

After drying, the two strips were exposed, developed, fixed and then dried. Strip A showed light and dark spots, while strip B was completely flawless.

Example 3 The gelatin interlayer, still wet, of a photographic material prepared as in Example 1, is contaminated with finely divided rust and other corrosion dust from the coating machinery (specimen A). For comparison the same material is employed, with the difference that its photosensitive emulsion contained kojic acid (Compound V in the table above) at 0.5 g./liter of emulsion. After drying, the two strips were exposed, developed, fixed and dried. Strip A shows dark spots, while strip B is completely flawless.

Example 4 The gelatin interlayer, still wet, of a photosensitive photographic material made according to Example 2 is contaminated with dust from powdered dye-containing antihalation layers, specimen A. In control specimen B the same material is employed, with the difference that its protective coating contains S-hydroxy-pyrone-(Z) (Compound I of the table above) at 5 g./ liter of the solution employed in making the protective coating.

After drying, the two strips are exposed, developed, fixed and dried. Strip A shows white spots while strip B is completely flawless.

The invention is not limited to incorporating the novel compounds shown above in photographic elements having gelatino-silver halide emulsions of the type given in the above examples. It may be applied to other simple and mixed silver halide emulsions. The emulsions can contain binding agents other than geltain or mixtures of gelatin and such binding agents. Suitable binding agents include polyvinyl alcohol and acetals thereof, polyvinyl pyrrolidone, polyvinvyl lactams, cellulose esters, dextrin These same water-permeable macromolecular organic and dextran, the latter two being mixed with gelatin. protective colloids and mixtures can be used for the subl-ayers, filter layers or protective layers.

The emulsions can contain color formers and other emulsion adjuvants including non-optical sensitizers such as sulfur sensitizers containing labile sulfur, e.g., allyl isothiocyanate allyl diethyl thiourea, phenyl isothiocyanate and sodium thiosulfate, the polyoxyalkylene ethers in Blake et al., US. 2,400,532 and the polyglycols disclosed in Blake et al., U.S. 2,423,549. Other nonoptical sensitizers such as amines as taught by Stand et al., US. 1,925,508 and metal salts as taught by Baldsiefen et al., US. 2,540,086 may also be used. Antifoggants, e.g., benzotriazole and triazaindenes, can be used as well as the usual hardeners, i.e., chrome alum, formaldehyde, etc.

The photographic emulsion or adhesive layer may be coated on any suitable support such as paper or films composed of cellulose esters, e.g., cellulose triacetate, cellulose acetate/butyrate, superpolymers, e.g., poly(vinyl chloride covinyl acetate) polyvinyl acetals, e.g., formals, acetals; polystyrene; polyamides, e.g., polyhexamethylene adipamide, and polyesters, e.g., polyethylene terephthalate, polyethylene terephthalate/isophthalate; esters formed by condensing terephthalic acid and dimethyl terephthalate with propylene glycol, tetramethylene glycol or cyclohexane-1,4-dimethanol (hexahydro-p-xylene alcohol). The vinylidene chloride copolymer-coated oriented polyester films of Allies US. 2,779,684 are especially suitable.

We claim:

1. A photographic element comprising a support bearing at least one silver halide emulsion layer, said element being characterized in that it has at least one waterpermeable organic colloid layer containing one or more compounds having the general formula:

in which x is a member selected from the group consisting of O- and and wherein R, R and R separately are each members selected from the group consisting of H, Cl, Br, alkyl of 1-4 carbons, acyl, carboxyl, carboxamide and carboxyalkyl of 2-5 carbons, and R and R when together constitute the atoms necessary to form an aromatic ring; R is a member selected from the group consisting of H, carboxyl, carboxamide and carboxyalkyl of 2-5 carbons; R is a member selected from the group consisting of H, alkyl of 1-4 carbons and carbalkoxy of 14 carbons, and R and R together constitute doubly bonded oxygen atom; and R is a member selected from the group consisting of H, alkyl of 1-4 carbon atoms, aralkyl and aryl.

2. An element according to claim 1 wherein said colloid is gelatin.

3. An element according to claim 1 having at least one gelatino-silver halide photographic emulsion layer.

4. An element according to claim 1 wherein the layer containing the compound is a gelatin layer contiguous with a gelatin-silver halide photographic emulsion layer.

5. An element according to claim 1 wherein said layer also contains an alkali metal salt of ethylenediaminetetraacetic acid.

6. A photographic element according to claim 1 wherein said colloid layer contains koiic acid.

10. A photographic element according to claim I having at least one water-permeable organic colloid layer containing kojic acid and an alkali metal salt of ethylenediaminetetraacetic acid.

8. An element according to claim 6 wherein the layer containing the compound is a gelatin layer contiguous with a gelatino-silver halide photographic emulsion layer.

9. A photographic element according to claim 1 having at least one water-permeable organic colloid layer containing maltol.

10. A photographic element according to claim 1 having at least one water-permeable organic colloid layer containing maltol and an alkali metal salt of ethylene diaminetetraacetic acid.

11. An element according to claim 10 wherein the layer containing the compound is a gelatin layer contigu ous with a gelatino-silver halide photographic emulsion layer.

References Cited UNITED STATES PATENTS 2,460,188 1/1949 OKane et al. 260345.9 2,845,349 7/1958 Schwarz 9666 3,130,204 4/1964 Tate et al. 260--345.9 3,138,556 6/1964 Goldsmith et al. 252136 3,186,853 6/1965 Meusel 99-140 3,305,363 2/1967 Beavers et al. 9695 3,310,405 3/1967 Bardorff et al 9694 OTHER REFERENCES Patuska et al.: Chemiker-Ztg. Chem. Apparatur, vol. 85, pp. 535-8 (1961).

20 J. TRAVIS BROWN, Primary Examiner. 

